Spectroscopic evaluation of Zn(PO3)2:Dy3+ glass as an active medium for solid state yellow laser

A spectroscopic investigation of zinc phosphate glass activated with 1.0, 5.0 and 10.0 mol% of Dy(PO₃)₃ is performed through absorption and luminescence spectra and decay times to study its potentialities for yellow laser operation upon excitation at 399 nm, which fits to the requirements of GaN LEDs. In the 1.0 mol% Dy(PO₃)₃-doped glass a quantum efficiency of 80 ± 5% was estimated for the dysprosium ⁴F_9/2 level luminescence, the ⁴F_9/2 → ⁶H_13/2 yellow emission shows greater intensity than the ⁴F_9/2 → ⁶H_15/2 blue emission, as well as a very high optical gain, which might make this glass phosphor a promising gain medium for solid state yellow laser pumped by GaN LEDs.     

Tunable luminescence of Dy3+ single-doped and Dy3+/Tm3+ co-doped tungsten borate glasses

RE³⁺ (RE³⁺ = Tm³⁺, Dy³⁺) ion single and co-doped tungsten borate glasses for white light emitting diodes (LEDs) were prepared by melt quenching method. Emission and excitation spectra of the glasses were measured. The color of luminescence can be tuned by changing the composition of glass matrix or the concentrations of Tm³⁺ and Dy³⁺ ions. White light emission can be achieved from 0.5Dy³⁺ single-doped 15WO₃–25La₂O₃–60B₂O₃ and 0.4Tm³⁺/1.5Dy³⁺ co-doped 50WO₃–25La₂O₃–25B₂O₃ glasses. In addition, energy transfers between Tm³⁺ and Dy³⁺ were also analyzed. The Dy³⁺/Tm³⁺ co-doped tungsten borate glasses may be potential candidates for white LED application.     

Spectroscopic properties of HoAl3(BO3)4 single crystal

The Judd–Ofelt theory has been applied to analyze absorption spectra of Ho³⁺ ion in HoAl₃(BO₃)₄ measured in spectral range 300–700 nm at room temperature. The Judd–Ofelt spectroscopic parameters have been determined as: Ω₂ = 18.87 × 10⁻²⁰ cm², Ω₄ = 17.04 × 10⁻²⁰ cm², Ω₆ = 9.21 × 10⁻²⁰ cm². These parameters have been used to calculate radiative lifetimes and branching ratios of the luminescence manifolds. Three luminescent bands were found in the spectral range 450–700 nm ascribed to transitions from the ⁵F₅, (⁵F₄, ⁵S₂) and ³K₈ states to the ground state ⁵I₈. Experimental intensities of these luminescence transitions were compared with those calculated by using Judd–Ofelt theory and the system of kinetic equations for populations of starting luminescing states. Probabilities of radiativeless transitions were evaluated from this comparison.     

Dielectrics of lead zirconate bonded with barium borate glass

Dielectric constant variation with temperature and frequency is reported for barium-borate glass-bonded lead zirconate. Lowering of the relative permittivity of the ceramic is attributed to the presence of the glass.     

Spectroscopic properties of Pr3+ and Er3+ ions in lead-free borate glasses modified by BaF2

Lead-free oxyfluoride borate glasses singly doped with Pr³⁺ and Er³⁺ were prepared and next investigated using absorption and luminescence spectroscopy. In the studied glass system, barium oxide was substituted by BaF₂. Two luminescence bands of Pr³⁺ located at visible spectral region are observed, which correspond to ³P₀–³H₄ (blue) and ¹D₂–³H₄ (reddish orange) transitions, respectively. The luminescence bands due to ¹D₂–³H₄ transition of Pr³⁺ are shifted to shorter wavelengths, when BaO was substituted by BaF₂. Near-infrared luminescence spectra of Er³⁺ ions in lead-free borate glasses modified by BaF₂ correspond to ⁴I_13/2–⁴I_15/2 transition. Their spectral linewidths increase with increasing BaF₂ concentration. The changes in measured lifetimes of rare earth ions are well correlated with the bonding parameters calculated from the optical absorption spectra.     

Effect of thermal annealing on the spectroscopic parameters of Er3+-doped sodium silicate glass

This paper presents the optical characteristics of Er³⁺ ions in sodium silicate glass (SiO₂–Na₂O), synthesized by the fusion method and later annealed for 0, 30, 60 and 90 min. Thermograms, X-ray diffraction, optical absorption, luminescence spectroscopy measurements were performed in order to determine the thermal and structural of the samples and the radiative characteristics of Er³⁺ ions under influence of thermal annealing of the samples. Differential thermal analysis provided evidence of a phase change in the system. This phase change was confirmed by X-ray diffraction, which showed the formation and growth of Na₂SiO₃ crystals for the annealed samples. These crystals affect the neighborhood (from second vicinity) of Er³⁺ ions. These effects were noted by the J–O parameters (Ω₂ and Ω₄), which were calculated from the optical absorption spectra. Judd–Ofelt calculations also confirmed that heat treatment induced structural rearrangement of the samples that was dependent on Er₂O₃ concentration. This resulted in changes in the optical and physical properties of the samples, including stimulated emission cross section and rigidity. Analysis of the spectroscopy parameters after of thermal annealing indicate samples are potential materials for in optical device applications.     

CaAlSiN3:Eu2+ phosphors bonding with bismuth borate glass for high power light excitation

The CaAlSiN₃:Eu²⁺ red phosphor-in-glass was prepared using bismuth borate glass as the binder for high power light excitation. B₂O₃–Bi₂O₃–Al₂O₃–ZnO glass powder showed good sintering behavior with CaAlSiN₃:Eu²⁺ phosphors at around 550 °C. The phosphor-in-glass has flat surface with a thickness of about 100 μm. From the images of FE-SEM and confocal laser scanning microscope, the uniform distribution of phosphor particles inside the phosphor-in-glass was vividly and clearly observed. And the luminescent property of phosphors was not greatly affected by glasses, as shown in fluorescence spectra. When the volume radio of CaAlSiN₃:Eu²⁺ phosphors was 50%, the sample exhibited low thermal quenching and high flexural strength of 28.5 MPa. Compared YAG:Ce³⁺ phosphor-in-glass with CaAlSiN₃:Eu²⁺ phosphor-in-glass, we found bismuth borate glass had better wettability on YAG:Ce³⁺ particles, which caused a higher flexural strength of the YAG:Ce³⁺ phosphor-in-glass.     

Spectroscopic investigations of Nd3+ ion in lead acetate glass

Using the optical absorption spectra and the Judd-Ofelt theory, intensity parameters (Ω_λ) are calculated. Radiative lifetimes (T _R), branching ratios (β) and integrated absorption cross sections (Σ) are reported for certain excited levels of Nd³⁺ ion in lead acetate glass.     

Judd–Ofelt and laser parameterization of Tm-doped barium gallo-germanate glass fabricated with efficient dehydration methods

Tm³⁺-doped barium gallo-germanate glasses were fabricated, and two efficient and easy-operated dehydration processes were conducted in the fabrication processes. Spectroscopic properties were obtained at room temperature, Judd–Ofelt parameters and laser parameters (absorption and emission cross-section, gain coefficient) were calculated using the McCumber (MC) theory and Fuchtbauer–Ladenburg (F–L) formula. Results indicate that barium gallo-germanate glass will be a good glass host for the 2.0-μm Tm³⁺-doped optical fiber laser. Factors influential to the population inversion of the ³F₄ level to the total rare-earth ions of the potential 2.0-μm Tm³⁺-doped optical fiber laser were analyzed using the rate equations.     

Generation of a long wedge-shaped barium atomic beam and its density characterization

A radiatively heated crucible having collinear array of channels has been used to produce a long wedge-shaped (length ∼100 mm, width ∼10 mm) high density (∼10¹¹ cm⁻³) atomic beam of barium. The collision-free beam flows upwards. The source is designed to generate atomic beams of low melting point (∼1000 K) metals and is suitable for long duration (∼15 h) operation. The beam, used for laser-ionized plasma studies, has been characterized by measuring the integrated density of the ground state of barium atoms at a fixed distance away from the source. At the same location the density distribution profiles along the length and width of the beam are also mapped. The measurements are carried out online using hollow cathode lamp based absorption spectroscopy technique and also intrusively by deposition method. The density and its distribution are also estimated theoretically. The data from the two experimental methods and estimates are in agreement within 10% accuracy.     

Structural and spectroscopic characteristics of Eu3+-doped tungsten phosphate glasses

Tungsten based phosphate glasses are interesting non-crystalline materials, commonly known for photochromic and electrochromic effects, but also promising hosts for luminescent trivalent rare earth ions. Despite very few reports in the literature, association of the host́s functionalities with the efficient emissions of the dopant ions in the visible and near-infrared spectra could lead to novel applications. This work reports the preparation and characterization of glasses with the new composition 4(Sb₂O₃)96−x(50WO₃ 50NaPO₃)xEu₂O₃ where x = 0, 0.1, 0.25, 0.5 and 1.0 mol%, obtained by the melt quenching technique. The glasses present large density (∼4.6 g cm⁻³), high glass transition temperature (∼480 °C) and high thermal stability against crystallization. Upon excitation at 464 nm, the characteristic emissions of Eu³⁺ ions in the red spectral region are observed with high intensity. The Judd–Ofelt intensity parameters Ω₂ = 6.86 × 10⁻²⁰, Ω₄ = 3.22 × 10⁻²⁰ and Ω₆ = 8.2 × 10⁻²⁰ cm² were calculated from the emission spectra and found to be higher than those reported for other phosphate glass compositions. An average excited state lifetime value of 1.2 ms, was determined by fitting the luminescence decay curves with single exponential functions and it is comparable or higher than those of other oxide glasses.     

Er~(3+)掺杂透明微晶玻璃光谱性质的研究

通过高温熔融法和热处理制备了含有-γBi2WO6纳米晶的Er3+掺杂透明硼铋酸盐微晶玻璃.根据X射线粉末衍射结果和Scherrer公式计算得到-γBi2WO6晶粒大小约为15 nm.由于部分Er3+离子取代Bi3+进入-γBi2WO6纳米晶相中,使得Er3+离子在1.5μm的有效发射带宽由78 nm增加到85 nm,同时Er3+离子在4I13/2能级的荧光寿命由0.67 ms增加到1.43 ms.此外,与原始玻璃相比,在Er3+掺杂硼铋酸盐微晶玻璃中观察到强烈的绿光上转换发光,其上转换发光机制可以归为双光子过程.     

Impact of Nd3+ ions on physical and optical properties of Lithium Magnesium Borate glass

Enhancing the up-conversion efficiency of borate glass via optimized doping of rare earth ions is an ever-ending quest in lasing glass. Neodymium (Nd³⁺) doped Lithium Magnesium Borate (LMB) glasses are prepared using the melt-quenching method. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), UV–Vis–NIR absorption and Photoluminescence (PL) spectroscopic characterizations are made to examine the influence of Nd³⁺ concentration on physical properties and optical properties. Nd³⁺ contents dependent density, molar volume, refractive index, ion concentration, Polaron radius, inter nuclear distance, field strength, energy band gap and oscillator strength are calculated. XRD patterns confirm the amorphous nature of all glasses and the FTIR spectra reveal the presence of BO₃ and BO₄ functional groups. UV–Vis–IR spectra exhibit ten prominent bands centered at 871, 799, 741, 677, 625, 580, 522, 468, 426, 349 nm corresponding to the transitions from the ground state to ⁴F_3/2, (⁴F_5/2 + ²H_9/2), (⁴F_7/2 + ⁴S_3/2), ⁴F_9/2, ²H_11/2, (⁴G_5/2 + ²G_7/2), (²K_13/2 + ⁴G_7/2 + ⁴G_9/2), (²G_9/2 + ²D_3/2 + ²P_3/2), (²P_1/2 + ²D_5/2), (⁴D_3/2 + ⁴D_5/2) excited states, respectively. A hyper-sensitive transition related to (⁴G_5/2 + ²G_7/2) level is evidenced at 580 nm. The room temperature up-conversion emission spectra at 800 nm excitation displays three peaks centered at 660, 610 and 540 nm. Glass with 0.5 mol% of Nd³⁺ showing an emission enhancement by a factor to two is attributed to the energy transfer between Mg²⁺ and Nd³⁺ ions. Our results suggest that these glasses can be nominated for solid state lasers and other photonic devices.     

掺铒铋酸盐玻璃光谱性质的混合形成体效应

测得了Er3+离子在铋酸盐玻璃系列(50～75)Bi2O3-(20～45)B2O3-5Na2O,70Bi2O3-(17～25)B2O3-xZrF4-5Na2O,70Bi2O3-(0～25)B2O3-(0～25)SiO2-5Na2O中的吸收光谱、荧光光谱及4I13/2能级荧光寿命.提出并研究了Er3+离子光谱性质的混合形成体效应,结果表明Er3+离子在铋酸盐玻璃中通过混合形成体效应可以获得较大的有效线宽(△λeff＝62～80nm)、较高的受激发射截面(σe＝0.76～0.84×10-20cm2)、较宽的荧光半高宽(FWHM＝55～80nm)以及较长的荧光寿命(τm＝1.6～4.3ms),说明掺Er3+铋酸盐玻璃是光纤放大器实现宽带和高增益放大较为理想的基质材料.     

Barium borosilicate glass as a matrix for the uptake of dyes

Barium borosilicate (BBS) and sodium borosilicate (SBS) glass samples, prepared by the conventional melt-quench method, were used for the uptake of Rhodamine 6G dye from aqueous solution. The experimental conditions were optimized to get maximum uptake and was found to be 0.4 mg of dye per gram of BBS glass sample. For the same network former to modifier ratio, barium borosilicate glasses are found to have improved extent of uptake for the dye molecules from aqueous solutions compared to sodium borosilicate glasses. Based on ²⁹Si MAS NMR studies on these glasses, it is inferred that significantly higher number of non-bridging oxygen atoms present in barium borosilicate glasses compared to sodium borosilicate glasses is responsible for its improved uptake of Rhodamine 6G dye. ¹¹B MAS NMR studies have confirmed the simultaneous existence of boron in BO₃ and BO₄ configurations in both barium borosilicate and sodium borosilicate glasses. The luminescence studies have established that the dye molecule is incorporated into the glass matrix through ion exchange mechanism by replacing the exchangeable ions like Na⁺/Ba²⁺ attached with the non-bridging oxygen atoms present in the glass.     

Observation of broadband infrared luminescence in a novel Bi-doped P2O5-B2O3-Al2O3 glass

A novel Bi-doped P₂O₅-B₂O₃-Al₂O₃ glass was investigated, and strong broadband NIR (near infrared) luminescence was observed when the sample was excited by 445 nm, 532 nm, 808 nm and 980 nm lasers, respectively. The max FWHM with 312 nm, the lifetime with 580 μs and the σ_emτ product with 5.3 × 10^− 24 cm² s were obtained which indicates that this glass is a promising material for broadband optical amplifier and tunable laser. The effect of the introduction of B₂O₃ on the glass structure and Bi-ions illuminant mechanism were discussed and analyzed. It is suggested that the introduction of B₂O₃ makes the glass structure closer, and the broadband NIR emission derives from Bi⁰:²D_3/2 → ⁴S_3/2 and Bi⁺:³P₁ → ³P₀ transitions.     

Plasmonic Au x Ag y bimetallic alloy nanoparticles enhanced photoluminescence upconversion of Er3+ ions in antimony glass hybrid nanocomposites

Er³⁺ ions and spherical (3–23?nm) Au _x Ag _y bimetallic alloy (where x?=?18–96 and y?=?4–82, atom %) nanoparticles incorporated novel antimony oxide based reducing dielectric (glass) matrix, K₂O–B₂O₃–Sb₂O₃ (KBS), has been synthesized by a new single step methodology involving selective thermochemical reduction. Their absorption spectra show a single tunable (536–679 nm) surface plasmon resonance band along with the typical absorption peaks of the Er³⁺ ion. X-ray and SAED indicate the formation of (111) and (200) planes of Au _x Ag _y alloy. The luminescence intensity of two prominent emission bands of Er³⁺ ions centered at 536 (green) and 645 (red) nm due to ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions were observed to be strongly dependent on the Au _x Ag _y nanoparticle composition. Both the bands undergo a maximum of 1.5- and 4.5-fold intensity enhancement respectively in the presence of the Ag₅₆Au₄₄ alloy (atom %) due to plasmon induced local field enhancement.     

Relationship between the local structure and spontaneous emission probability of Er3+ in silicate,borate, and phosphate glasses

Extended X-ray absorption fine structure (EXAFS) measurements have been performed on Er³¹ in silicate, borate, and phosphate glasses in order to investigate the local structure surrounding the Er³¹.Er³¹ ions coordinate to non-bridging oxygen ion sites, where alkali or alkaline earth ions terminate the network structure of silicate glasses. In borate glasses, the local structure surrounding Er³¹ ions is altered by the structural change ofthe borate anion. Er³¹ ions coordinate to non-bridging oxygen ion sites and BO₄ structural units in the cases with and without the formation of non-bridging oxygen, respectively. The former is similar to the case in silicate glasses. Er³¹ ions selectively coordinate to the PyO site regardless of the glass composition variation. A correlation was observed between the spontaneous emission probability for ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ and the average Er–O distance calculated by EXAFS analysis. It shows the maximum value near 2.32 Å, and we conclude that the overlapping radial integral of the 4f and 5d orbitals of Er³⁺ would be the largest at the optimum Er³¹– O²² distance 2.3 Å.     

Thermal analysis of a diffusion bonded Er3+,Yb3+:glass/Co2+: MgAl2O4 microchip lasers

The analysis of thermal effects in a diffusion bonded Er³⁺,Yb³⁺:glass/Co²⁺:MgAl₂O₄ microchip laser is presented. The analysis is performed for both wavelengths at 940 nm and at 975 nm as well as for two different sides of pumping, glass side and saturable absorber side. The heat sink effect of Co²⁺:MgAl₂O₄, as well as the impact of the thermal expansion and induced stress on the diffusion bonding are emphasised. The best configurations for reducing the temperature peaks, the Von Mises stresses on the diffusion bonding, and the thermal lensing are determined.